1. Field of the Invention
This invention comprises a screwdriver and more particularly it comprises a multi-bit, dual-mode screwdriver with integral bit storage and adapted for use in either a manual or powered mode of actuation.
2. Background of the Invention
Prior art replaceable-tip screwdrivers (“bit-holders”) are generally for either handheld operation (“manual-driving mode”) or for use with a powered means of rotation such as an electric drill (“power-driving mode”).
Many prior art bit-holders exist for manual-driving. Relevant handheld devices are taught by: Kozak (U.S. Pat. No. 6,629,478), Cluthe (U.S. Pat. No. 6,332,384), Wu (U.S. Pat. No. 6,3052,55), McKenzie (U.S. Pat. No. 4,924,733), Kikel (U.S. Pat. No. 4,848,197) and Trincia (U.S. Pat. No. 4,434,828). These handheld devices suffer from either limited bit. storage capacity (generally six or less) or else utilize cumbersome and complex bit change mechanisms. Kikel's, Kozak's and Wu's device all teach an opposing bit socket configuration that enables the user to manually actuate either of two mounted bits, however none of them teach a power driving mode. Wannop (U.S. Pat. No. 6,601,483), Sato (U.S. Pat. No. 6,205,893) and Shiao (U.S. Pat. No. 6,134,995), Yanugi et al. (U.S. Pat. No. 5,673,600), Koehler (U.S. Pat. No. 5,325,745) and Orlitzky (U.S. Pat. No. 4,762,036) teach manual mode devices that provide more rapid and easy bit changing than the devices cited above however their extra degree of automation comes at the expense of greater bulk and mechanical complexity.
The other cluster of relevant prior art bit-holders are for actuation by powered means such as an electric drill: Beauchamp U.S. Pat. No. 6,761,095, Jui-Tung Chen (U.S. Pat. No. 6,742,421),Wadsworth (U.S. Pat. No. 6,752,268), Robison (U.S. Pat. No. 5,921,562), Hogan (U.S. Pat. No. 5,597,275) and Lore (U.S. Pat. No. 5,309,799) teach bit holders that operate exclusively in power-driving mode. They also require a fairly large rotating diameter which limits bit access into tight quarters.
My search of the prior art has revealed only one “dual-mode” bit holder. Pending application Beauchamp (US 20030079581) includes a threaded rear extension that can be attached to the handgrip portion of a manual screwdriver to render the device suitable for power-driving. Beauchamp's design requires a separate gripping adaptor to enable the device's power driving mode (his adaptor being screwed onto the rear portion of the handgrip as shown in his FIG. 17 and FIG. 29). This single-purpose gripping means complicates the device's construction as well as rendering it cumbersome to use.
In summary: the prior art devices suffer from one or more of several drawbacks:                1. They are limited to either manual-driving mode or power-driving mode.        2. Their bit storage capacity is too small to accommodate a wide selection of bits.        3. Their stored screwdriver tips are not readily visible, thereby slowing down the bit-selection process.        4. Their bit storage mechanism is bulky and/or cumbersome to manipulate.        5. Their handle for manual operation doesn't present an ergonomic means for applying axial force while turning the active screwdriver bit.        6. Their structure is complex with many discrete or moving parts.        7. Their screwdriver bits cannot be easily gripped by a user in order to pull them from their magnetic drive sockets.        
It is therefore desirable to provide a simpler and more efficient screwdriver that can easily be used in either manual-driven mode or power-driven mode and that minimizes those drawbacks observed in the single-mode devices.